The movements involved in flight of some missiles and space vehicles, such as pitch, yaw, and spin rate, are controlled with flight control systems that use reaction jets. In some systems of this type, a pressurized gas source, such as a gas generator, supplies a pressurized gas to one or more fluidic amplifier stages. In response to a control signal supplied from flight control equipment, a fluidic amplifier stage can selectively divert the pressurized gas into one of two or more flow paths. Each flow path may have a nozzle on its outlet that is located external to the missile or vehicle. These nozzles may be positioned to provide thrust in different or opposite directions. Thus, the fluidic amplifier stages can affect one or more flight parameters by selectively diverting the pressurized gas to selected outlet nozzles.
The fluidic amplifier stages incorporated into the above-described flight control system can include non-vented fluidic amplifiers, which are generally known in the art. However, non-vented fluidic amplifiers may not provide 100% flow diversion. Thus, some systems incorporate an additional fluidic element, such as a fluidic diverter valve, between the final fluidic amplifier stage and the output nozzles, which allows the system to substantially achieve 100% flow diversion.
One particular type of fluidic diverter valve uses a spherically shaped ball valve element. The ball element is solid, and is located in a chamber formed in the valve housing. The housing includes an inlet port and two outlet ports. The ball element is moveable within the chamber and selectively blocks one of the two ports so that pressurized gas entering the inlet port is selectively directed out the port that is not blocked. For high-temperature applications, such as those that may be encountered in missile and spacecraft propulsion systems, refractory metals, such as rhenium, and carbon-based materials, such as graphite, may be used to construct the valve element. In some cases, rhenium coated graphite valve elements are used.
Although the above-described type of fluidic diverter valve is robustly designed and manufactured, and operates safely, it suffers certain drawbacks. For example, the impact load experienced by the valve element during operation can cause cracks in the rhenium coating, which can adversely impact system performance, shorten valve element lifetime, and/or increase overall system costs.
Hence, there is a need for a fluidic diverter valve that addresses one or more of the above-noted drawbacks. Namely, a hot gas fluidic diverter valve having a valve element that experiences reduced impact loading during operation, and thus does not adversely impact system performance, and/or does not shorten valve element lifetime, and/or does not increase overall system cost. The present invention addresses one or more of these needs.